the emails ive been getting make it appear that they don't have special coupons. they've got doorbuster items on the site in addition to the regular sale items and shipping is free over $50 without a code.
I used ONSAVE20 a couple days a go for 20 percent off and they also gave me free shipping. I am not sure if it still works or if someone put it up, but I thought I would add this. And if you find Old Navy on facebook (That is where I cound that code) other people update codes on there as well.